Malaria Vaccine TrialSource:
Volunteer patients were randomized into one of two experiment groups where they would receive an experimental vaccine or a placebo. They were subsequently exposed to a drug-sensitive strain of malaria and observed to see whether they came down with an infection.
A data frame with 20 observations on the following 2 variables.
Whether a person was given the experimental
Whether the person got an
Lyke et al. 2017. PfSPZ vaccine induces strain-transcending T cells and durable protection against heterologous controlled human malaria infection. PNAS 114(10):2711-2716. doi: 10.1073/pnas.1615324114 .
In this study, volunteer patients were randomized into one of two experiment groups: 14 patients received an experimental vaccine or 6 patients received a placebo vaccine. Nineteen weeks later, all 20 patients were exposed to a drug-sensitive malaria virus strain; the motivation of using a drug-sensitive strain of virus here is for ethical considerations, allowing any infections to be treated effectively.
library(dplyr) # Calculate conditional probabilities of infection after vaccine/placebo malaria %>% count(treatment, outcome) %>% group_by(treatment) %>% mutate(prop = n / sum(n)) #> # A tibble: 3 × 4 #> # Groups: treatment  #> treatment outcome n prop #> <fct> <fct> <int> <dbl> #> 1 placebo infection 6 1 #> 2 vaccine infection 5 0.357 #> 3 vaccine no infection 9 0.643 # Fisher's exact text fisher.test(table(malaria)) #> #> Fisher's Exact Test for Count Data #> #> data: table(malaria) #> p-value = 0.01409 #> alternative hypothesis: true odds ratio is not equal to 1 #> 95 percent confidence interval: #> 1.338381 Inf #> sample estimates: #> odds ratio #> Inf #>